//! Optimism Consensus implementation.

#![doc(
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#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
#![cfg_attr(not(feature = "std"), no_std)]
// The `optimism` feature must be enabled to use this crate.
#![cfg(feature = "optimism")]

extern crate alloc;

use core::fmt::Debug;

use alloc::sync::Arc;
use alloy_consensus::{BlockHeader as _, EMPTY_OMMER_ROOT_HASH};
use alloy_primitives::{B64, U256};
use reth_chainspec::{EthChainSpec, EthereumHardforks};
use reth_consensus::{
    Consensus, ConsensusError, FullConsensus, HeaderValidator, PostExecutionInput,
};
use reth_consensus_common::validation::{
    validate_against_parent_4844, validate_against_parent_eip1559_base_fee,
    validate_against_parent_hash_number, validate_against_parent_timestamp,
    validate_body_against_header, validate_cancun_gas, validate_header_base_fee,
    validate_header_extra_data, validate_header_gas, validate_shanghai_withdrawals,
};
use reth_optimism_forks::OpHardforks;
use reth_optimism_primitives::DepositReceipt;
use reth_primitives::{GotExpected, NodePrimitives, RecoveredBlock, SealedHeader};

mod proof;
pub use proof::calculate_receipt_root_no_memo_optimism;
use reth_primitives_traits::{Block, BlockBody, BlockHeader, SealedBlock};

mod validation;
pub use validation::{
    decode_holocene_base_fee, next_block_base_fee, validate_block_post_execution,
};

/// Optimism consensus implementation.
///
/// Provides basic checks as outlined in the execution specs.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct OpBeaconConsensus<ChainSpec> {
    /// Configuration
    chain_spec: Arc<ChainSpec>,
}

impl<ChainSpec> OpBeaconConsensus<ChainSpec> {
    /// Create a new instance of [`OpBeaconConsensus`]
    pub const fn new(chain_spec: Arc<ChainSpec>) -> Self {
        Self { chain_spec }
    }
}

impl<ChainSpec: EthChainSpec + OpHardforks, N: NodePrimitives<Receipt: DepositReceipt>>
    FullConsensus<N> for OpBeaconConsensus<ChainSpec>
{
    fn validate_block_post_execution(
        &self,
        block: &RecoveredBlock<N::Block>,
        input: PostExecutionInput<'_, N::Receipt>,
    ) -> Result<(), ConsensusError> {
        validate_block_post_execution(block.header(), &self.chain_spec, input.receipts)
    }
}

impl<ChainSpec: EthChainSpec + OpHardforks, B: Block> Consensus<B>
    for OpBeaconConsensus<ChainSpec>
{
    type Error = ConsensusError;

    fn validate_body_against_header(
        &self,
        body: &B::Body,
        header: &SealedHeader<B::Header>,
    ) -> Result<(), ConsensusError> {
        validate_body_against_header(body, header.header())
    }

    fn validate_block_pre_execution(&self, block: &SealedBlock<B>) -> Result<(), ConsensusError> {
        // Check ommers hash
        let ommers_hash = block.body().calculate_ommers_root();
        if Some(block.ommers_hash()) != ommers_hash {
            return Err(ConsensusError::BodyOmmersHashDiff(
                GotExpected {
                    got: ommers_hash.unwrap_or(EMPTY_OMMER_ROOT_HASH),
                    expected: block.ommers_hash(),
                }
                .into(),
            ))
        }

        // Check transaction root
        if let Err(error) = block.ensure_transaction_root_valid() {
            return Err(ConsensusError::BodyTransactionRootDiff(error.into()))
        }

        // EIP-4895: Beacon chain push withdrawals as operations
        if self.chain_spec.is_shanghai_active_at_timestamp(block.timestamp()) {
            validate_shanghai_withdrawals(block)?;
        }

        if self.chain_spec.is_cancun_active_at_timestamp(block.timestamp()) {
            validate_cancun_gas(block)?;
        }

        Ok(())
    }
}

impl<ChainSpec: EthChainSpec + OpHardforks, H: BlockHeader> HeaderValidator<H>
    for OpBeaconConsensus<ChainSpec>
{
    fn validate_header(&self, header: &SealedHeader<H>) -> Result<(), ConsensusError> {
        validate_header_gas(header.header())?;
        validate_header_base_fee(header.header(), &self.chain_spec)
    }

    fn validate_header_against_parent(
        &self,
        header: &SealedHeader<H>,
        parent: &SealedHeader<H>,
    ) -> Result<(), ConsensusError> {
        validate_against_parent_hash_number(header.header(), parent)?;

        if self.chain_spec.is_bedrock_active_at_block(header.number()) {
            validate_against_parent_timestamp(header.header(), parent.header())?;
        }

        // EIP1559 base fee validation
        // <https://github.com/ethereum-optimism/specs/blob/main/specs/protocol/holocene/exec-engine.md#base-fee-computation>
        // > if Holocene is active in parent_header.timestamp, then the parameters from
        // > parent_header.extraData are used.
        if self.chain_spec.is_holocene_active_at_timestamp(parent.timestamp()) {
            let header_base_fee =
                header.base_fee_per_gas().ok_or(ConsensusError::BaseFeeMissing)?;
            let expected_base_fee =
                decode_holocene_base_fee(&self.chain_spec, parent.header(), header.timestamp())
                    .map_err(|_| ConsensusError::BaseFeeMissing)?;
            if expected_base_fee != header_base_fee {
                return Err(ConsensusError::BaseFeeDiff(GotExpected {
                    expected: expected_base_fee,
                    got: header_base_fee,
                }))
            }
        } else {
            validate_against_parent_eip1559_base_fee(
                header.header(),
                parent.header(),
                &self.chain_spec,
            )?;
        }

        // ensure that the blob gas fields for this block
        if let Some(blob_params) = self.chain_spec.blob_params_at_timestamp(header.timestamp()) {
            validate_against_parent_4844(header.header(), parent.header(), blob_params)?;
        }

        Ok(())
    }

    fn validate_header_with_total_difficulty(
        &self,
        header: &H,
        _total_difficulty: U256,
    ) -> Result<(), ConsensusError> {
        // with OP-stack Bedrock activation number determines when TTD (eth Merge) has been reached.
        debug_assert!(
            self.chain_spec.is_bedrock_active_at_block(header.number()),
            "manually import OVM blocks"
        );

        if header.nonce() != Some(B64::ZERO) {
            return Err(ConsensusError::TheMergeNonceIsNotZero)
        }

        if header.ommers_hash() != EMPTY_OMMER_ROOT_HASH {
            return Err(ConsensusError::TheMergeOmmerRootIsNotEmpty)
        }

        // Post-merge, the consensus layer is expected to perform checks such that the block
        // timestamp is a function of the slot. This is different from pre-merge, where blocks
        // are only allowed to be in the future (compared to the system's clock) by a certain
        // threshold.
        //
        // Block validation with respect to the parent should ensure that the block timestamp
        // is greater than its parent timestamp.

        // validate header extra data for all networks post merge
        validate_header_extra_data(header)?;

        // mixHash is used instead of difficulty inside EVM
        // https://eips.ethereum.org/EIPS/eip-4399#using-mixhash-field-instead-of-difficulty

        Ok(())
    }
}
